[Xen-changelog] [xen stable-4.12] x86/efi: properly handle 0 in pixel reserved bitmask

[patchbot@xxxxxxx]

commit c28853456b51516514d36659494fbe7c1d983e2c
Author:     Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
AuthorDate: Fri Oct 25 11:43:49 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Oct 25 11:43:49 2019 +0200

    x86/efi: properly handle 0 in pixel reserved bitmask
    
    In some graphics modes firmware is allowed to return 0 in pixel reserved
    bitmask which doesn't go against UEFI Spec 2.8 (12.9 Graphics Output 
Protocol).
    
    Without this change non-TrueColor modes won't work which will cause
    GOP init to fail - observed while trying to boot EFI Xen with Cirrus VGA.
    
    Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 521a1445510a30873aec471194045e7f4b5e8d75
    master date: 2019-10-10 16:50:50 +0200
---
 xen/arch/x86/efi/efi-boot.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 7a13a30bc0..dee65b7177 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -528,9 +528,10 @@ static void __init 
efi_arch_video_init(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
         bpp = set_color(mode_info->PixelInformation.BlueMask, bpp,
                         &vga_console_info.u.vesa_lfb.blue_pos,
                         &vga_console_info.u.vesa_lfb.blue_size);
-        bpp = set_color(mode_info->PixelInformation.ReservedMask, bpp,
-                        &vga_console_info.u.vesa_lfb.rsvd_pos,
-                        &vga_console_info.u.vesa_lfb.rsvd_size);
+        if ( mode_info->PixelInformation.ReservedMask )
+            bpp = set_color(mode_info->PixelInformation.ReservedMask, bpp,
+                            &vga_console_info.u.vesa_lfb.rsvd_pos,
+                            &vga_console_info.u.vesa_lfb.rsvd_size);
         if ( bpp > 0 )
             break;
         /* fall through */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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